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首页> 外文期刊>Physical review >Projector augmented wave calculation of x-ray absorption spectra at the L_(2,3) edges
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Projector augmented wave calculation of x-ray absorption spectra at the L_(2,3) edges

机译：L_（2,3）边缘的X射线吸收光谱的投影仪增强波计算

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We develop a technique based on density functional theory and the projector augmented wave method in order to obtain the x-ray absorption cross section at a general edge, both in the electric dipole and quadrupole approximations. The method is a generalization of Taillefumier et al., [Phys. Rev. B 66, 195107 (2002)]. We apply the method to the calculation of the Cu L_(2,3) edges in fcc copper and cuprite (Cu_2O), and to the S L_(2,3) edges in molybdenite (2H-MoS_2). The role of core-hole effects, modeled in a supercell approach, as well as the decomposition of the spectrum into different angular momentum channels are studied in detail. In copper we find that the best agreement with experimental data is obtained when core-hole effects are neglected. On the contrary, core-hole effects need to be included both in Cu_2O and 2H-M0S2. Finally we show that a non-negligible component of S L_(2,3) edges in 2H-M0S2 involves transition to states with s character at all energy scales. The inclusion of this angular momentum channel is mandatory to correctly describe the angular dependence of the measured spectra. We believe that transitions to s character states are quantitatively significant at the L_(2,3) edges of third row elements from Al to Ar.
机译：我们开发了一种基于密度泛函理论和投影仪增强波方法的技术，以便在电偶极子和四极子近似中获得一般边缘的X射线吸收截面。该方法是Taillefumier et al。，[Phys。 B 66，195107（2002）。我们将该方法应用于fcc铜和铜矿（Cu_2O）中的Cu L_（2,3）边缘，以及辉钼矿（2H-MoS_2）中的S L_（2,3）边缘的计算。详细研究了以超级单元方法建模的芯孔效应的作用，以及将光谱分解为不同的角动量通道。在铜中，我们发现当忽略芯孔效应时，可以获得与实验数据的最佳一致性。相反，Cu_2O和2H-M0S2都需要包含芯孔效应。最后，我们证明2H-M0S2中S L_（2,3）边的不可忽略的分量涉及到在所有能级上转变为s特性的状态。必须包含此角动量通道，才能正确描述所测光谱的角度依赖性。我们认为，在从Al到Ar的第三行元素的L_（2,3）边缘，从s字符状态的转变在数量上很重要。

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